In the related art, there has been known an internal combustion engine which recirculates blow-by gas, which leaks into a crankcase of the internal combustion engine, to an engine intake system (intake system) (e.g., see JP 02-188612 A (Reference 1)).
The internal combustion engine disclosed in Reference 1 has a cylinder block in which cylinders are disposed, a cylinder head which is fixed to an upper end portion of the cylinder block, and an oil pan which is fixed to a lower end portion of the cylinder block. In addition, the cylinder block includes a crankcase disposed below a crankshaft.
Here, in the internal combustion engine disclosed in Reference 1, blow-by gas produced in the cylinders by combustion of fuel does not flow to an exhaust manifold but leaks into the crankcase and accumulates in the crankcase. For this reason, the internal combustion engine disclosed in Reference 1 is provided with a blow-by gas passageway that recirculates the blow-by gas accumulated in the crankcase to the engine intake system. The blow-by gas passageway has an opening formed in an inner surface portion of the crankcase, and includes a first blow-by gas passageway (intake passageway) in which the blow-by gas flows. Further, the opening formed in the inner surface portion of the crankcase is opened in a direction orthogonal to a direction in which the crankshaft extends.
However, since the opening of the blow-by gas passageway formed in the inner surface portion of the crankcase of the internal combustion engine disclosed in Reference 1 is opened in the direction orthogonal to the direction in which the crankshaft extends, oil, which is scattered in the crankcase by the rotation of the crankshaft, is attached to the opening of the blow-by gas passageway such that the oil is likely to be drawn into a first blow-by gas passageway. In this case, the oil drawn into the first blow-by gas passageway flows into combustion chambers from the engine intake system, and as a result, a problem occurs with respect to combustion in the combustion chambers. For this reason, there is a demand for an internal combustion engine capable of inhibiting the oil from penetrating into the blow-by gas passageway.
Thus, a need exists for an internal combustion engine which is not susceptible to the drawback mentioned above.